The present invention relates to an electric vehicle driven by a secondary battery, more particularly to a charge/discharge control of the secondary battery for the electric vehicle.
Performance and reliability of secondary batteries such as lead acid storage batteries, nickel-metal hydride storage batteries and lithium secondary batteries have been improved in these days. Consequently, there have been also developed many devices driven by the secondary batteries. Especially, in recent years, clean energies are aimed widely and electric vehicles such as electromobiles, motor scooters, forklifts which are driven by the secondary batteries are attracting a great deal of attention.
In such an electric vehicle, a vehicle controller mounted in an object vehicle controls the output of the motor, and also monitors and controls the batteries. Monitoring a remaining capacity, an output voltage, and a cooling state, or the like of the batteries installed in the vehicle, the vehicle controller decides the battery state including the level of degradation thereby to control the output of the motor and charging of the battery based on the obtained battery information. In addition, the vehicle controller issued warnings to the driver if necessary.
In the case of a conventional electric vehicle, the battery is considered to be a mere driving power source. The vehicle controller is thus fixed to a vehicle. Therefore, when the battery is degraded or down, the battery is just replaced. Consequently, each time the battery is replaced with a different specification, the vehicle controller set values must be changed so as to correspond with the new battery.